Carrying Capacity

By Ashhad A. Khan

Dec 21, 2009

Modern science and writings often lay the blame for the destruction of humans on humankind for its unconscientious plundering of Earth's resources. This theory brings up additional questions, such as how long will Earth be able to sustain this consumptive behavior and how should human behavior change to protect the planet for future generations.

The answers may be many but one thing is common: Researchers must analyze Earth's carrying capacity—that particular size of population that Earth can sustain indefinitely—in regards to the availability of food, shelter, water, fuel, energy, etc, and in such a way so as to prevent the degeneration of the natural environment for the future. In the last 160 years, Earth's population grew by 5.5 billion—from 1.2 billion in 1850 to the current level of 6.7 billion people—and is projected to reach 9.5 billion in about 40 years.

Should these trends continue, the ability of the Earth to support the human race will be called into question.

When analyzing carrying capacity, researchers need to remember that global or even regional population size is not the primary factor. The amount of resources the population uses to sustain itself is most important. For example, the Netherlands, with an area of 33,920 square kilometer and a human population density of 440 people per kilometer, depends on the ecological productivity or carrying capacity of an area almost 15 times larger than that of the entire country. Of course, at a regional level the population can use more than the locally available resources due to massive globalization and international trade, but at a global level, an ecological deficit will severely affect the natural environment, denigrating it to the point of uselessness for future generations.

Today's global average bio-capacity (the number of resources generated by the Earth in that year) is 2.1 hectares per person. Meanwhile, the total global ecological footprint stands at 2.7 hectares per person. Obviously, we are living beyond our means. At the moment, we need 1.3 Earths to effectively sustain our collective way of life. According to the Global Footprint Network, we will need two Earths to support us by the mid-2030s if population and consumption trends continue. The overshoot of resources is expected to contribute to problems like resource wars, diseases, famines, mass migration and will tend to have a disproportionate impact on the poor.

In 2006, the total global energy consumption was 15.8 Terawatts (TW). Out of this, 13.6 TW or 86 percent was provided by nonrenewable oil, coal and gas. Nuclear fuel, which has been offered as a solution to the world's energy needs, comes with a different kind of cost. Chernobyl effectively limited the viability of nuclear power. Despite many precautions taken to mitigate the risks, the possibility of a repeat of Chernobyl exists, at the very least statistically.

Tragic and desperate as the circumstances of carrying capacity and resources sound, there are more options to try to reverse the ecological deficit and live within Earth's means.

One of the more sustainable alternatives is solar energy. In 2005, the energy consumed through solar power was roughly 0.15 percent of total energy consumed. The usable solar energy available is 3.8 YJ (1 YJ=10^24 Joules) per year, around 8,000 times as much as the total energy consumption in 2005 and close to 50,000 times that of the total solar energy consumed that year.

To be able to harvest power from the sun efficiently would provide a never-ending source of energy without any lasting damage to the environment. It would remove our dependence on oil, gas and coal. Solar research would need to be done on a global scale and would require immense funding.

Current work under way includes some cost-cutting research:

Soliant Energy, a startup based in Pasadena, Calif., is developing a system that has a mechanism that focuses sunlight on small areas of photovoltaic cells. This approach has the potential to make solar power cheaper than electricity from the grid in most markets, due to the fact that less photovoltaic material will be needed.

A team of researchers led by University of Johannesburg’s Professor Vivian Alberts is working on using a thin, flexible sheet of copper-indium-gallium-diselenide alloy to replace silicon-based photovoltaic cells. This may reduce the cost of solar energy by five times the cost of silicon-based photovoltaic cells.

But the most crucial way to effect change is to bring it about by oneself. Little things all come together to create huge environmental solutions. Turning off the plasma TV when it's not in use, taking quick showers, recycling paper and using non-biodegradable plastic shopping bags help reduce our ecological footprints. Even more beneficial would be carpooling with colleagues. A group of four colleagues sharing the ride contributes only a quarter as much to the ecological footprint than each of them individually. Of course, these are personal matters and only an individual's conscience can compel him or her toward the path of sustainability.

The rewards of making changes now will one day be apparent; maybe not in our lifetime, but most certainly in that of our grandchildren. Unfortunately, so will the consequences of inaction.

About the Author

Ashhad A. Khan is a chemical engineering graduate from the University at Buffalo who is interested in sustainability, water resource engineering, alternative energy, and other environmental issues.